TACOMA, Wash. -- A fourth demonstrator was arrested early Tuesday in anti-war protests at the Port of Tacoma as protesters and police in riot gear faced off for the second day.

Slideshow: Police, Protesters Face Off

Police told protesters to stay behind a white line while military equipment was transported for shipment to Iraq, but a woman was arrested after she crossed the boundary.

Video: Demonstrator Arrested In Port Protest

Demonstrators sang the hokey pokey, trying to see how far they could push police, said KIRO 7 Eyewitness News reporter Lori Nixon.

Demonstrators continued the protests Tuesday afternoon by gathering at Tacoma's Federal building.

Three protesters from Olympia were arrested on Monday morning and booked into jail on suspicion of third-degree assault. They were scheduled to appear in court on Tuesday.

The Army is shipping equipment through Tacoma for a Stryker brigade that is being sent to Iraq. The military convoys will continue through the week.

Officials at Fort Lewis won't say when the equipment will be loaded onto a ship.

Similar shipments drew widespread protests and dozens of arrests during demonstrations last year at the Port of Olympia.